Compact and durable encasement for a digital radiography detector

ABSTRACT

A digital radiography detector includes a housing and a radiographic image detector assembly. The housing has a first and second spaced planar members and four side walls defining a cavity. The radiographic image detector assembly is mounted within the cavity for converting a radiographic image to an electronic radiographic image. The detector assembly includes a scintillator screen and a detector array, and the detector assembly is bonded to the first planar member of the housing.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Divisional of commonly assigned application U.S. Ser. No.12/354,839, entitled “COMPACT AND DURABLE ENCASEMENT FOR A DIGITALRADIOGRAPHY DETECTOR”, filed on Jan. 16, 2009 in the names of Jadrich etal., which is a Divisional of U.S. Ser. No. 11/441,584 entitled “COMPACTAND DURABLE ENCASEMENT FOR A DIGITAL RADIOGRAPHY DETECTOR”, filed on May26, 2006 in the names of Jadrich et al.

FIELD OF THE INVENTION

This invention relates in general to medical imaging systems which usedigital radiography detectors, and more particularly to a compact anddurable encasement or housing for a digital radiography detector.

BACKGROUND OF THE INVENTION

Traditional film-screen radiography has been used as a medical imagingdiagnostic system for many years. X-rays are projected through apatient's body part to form a latent radiographic image on filmcontained in a cassette. The film is then be chemically or thermallyprocessed to produce a visual radiographic image which can be used by ahealth care professional for diagnostic purposes. The delay in obtaininga diagnostic image, the use of a chemical or thermal processor, and thedifficulty in providing the radiographic film outside of the immediatemedical facility, has resulted in the development of digitalradiographic imaging systems. Computed radiography (CR) digital systemshave been developed in recent years that provide reusable CR plateswhich are scanned to produce a digital radiographic image. The CRsystems still result in a delay in obtaining a diagnostic image due tothe necessity of scanning an exposed CR plate.

Digital radiography is achieving a growing acceptance as an alternativeto film-screen and CR radiography systems. With digital radiography(DR), the radiation image exposures captured on radiation sensitivelayers are converted, pixel by pixel, to digital image data which isstored and subsequently displayed on electronic display devices. One ofthe driving forces in the success of digital radiography is the abilityto rapidly visualize and communicate a radiographic image via networksto a remote location for analysis and diagnosis by radiologists withoutthe delay in sending chemically or thermally processed radiographicfilms by courier or through the mail. The use of chemical or thermalprocessors is also eliminated by digital radiography systems.

The solid-state, ionizing radiation based image detectors used inprojection digital radiography today are relatively large, heavy, andexpensive. Additionally, a complete DR systems using this type ofdetector (hereafter DR detector) requires substantial capital investmentto retrofit with existing X-ray equipment. For projection radiography,the detector array in these systems is typically a large-area pixilateddevice, fabricated on a glass substrate. The large-area detector arrayis expensive to fabricate, and it is also fragile to handle since thesubstrate is glass. As a result, DR detectors and systems are veryexpensive and the current market is small given the high cost ofinvestment.

DR detectors can either be direct or indirect conversion devices. Directdetectors use a material such as selenium in contact with a TFT arrayfor conversion of X-ray photons. Indirect detectors use a scintillatorscreen for conversion of X-rays to visible light, through contact with asilicon photodiode and TFT array.

The dimensions of medical radiographic cassettes/screens/films arespecified under ISO 4090:2001(E) standard. This includes bothconventional film and CR phosphor screens, with nominal imaging areas upto 35 cm×43 cm and 40 cm×40 cm (metric origin). Standard cassettedimensions are also specified as part of the ISO standard, including themaximum cassette thickness of 16.0 mm.

U.S. Pat. No. 5,844,961, issued Dec. 1, 1998, inventors McEvoy et al.,discloses a filmless digital x-ray system that uses a standard x-raycassette housing. An external power source provides the power for thedetector and associated electronic system.

U.S. Patent Application Publication No. 2004/0227096, published Nov. 18,2004, inventor Yagi, discloses a metal spring assembly for providingshock isolation to a radiation detector that provides limited shockisolation due to the stiffness of the metal type spring.

U.S. Patent Application Publication No. 2005/0017188, published Jan. 27,2005, inventor Yagi, discloses means to provide shock isolation to aradiation detector, in which shock absorption material is providedbetween inner and outer frames. This structure increases the size of thecassette.

U.S. Pat. No. 6,296,386, issued Oct. 2, 2001, inventors Heidsieck etal., discloses a cassette for producing images for a radiographyapparatus intended for mobile type cassettes. A handle and locking meansare disclosed for locating the cassette within a reception housing. Itis intended for use with mammography exposure devices, where lockingfeatures are advantaged since the reception housing can be in multipleorientations, where the cassette would be susceptible to dropping. Thefeatures disclosed are larger than the standard cassette and extend tocontact the reception housing. This can limit its usage to specifictypes of x-ray equipment.

U.S. Pat. No. 6,855,936, issued Feb. 15, 2005, inventor Yamamoto,discloses a cassette for use in a portable imaging environment. Thecassette has a plurality of electrical connecting ports and a pluralityof fixed handles. These allow for multiple detector orientation forspecific radiographic exposures.

U.S. Pat. No. 6,805,484, issued Oct. 19, 2004, inventors Kuramoto etal., discloses a portable device with at least one handle secured to thedevice housing. This handle is movably connected or pivoted, for thepurpose of facilitating patient positioning only.

U.S. Pat. No. 6,700,126, issued Mar. 2, 2004, inventor Watanabe,discloses a radiation detector which includes a shock absorber placed onany one of the side walls of the cassette. While this provides somelateral protection to the detector, it does not provide protection inthe direction orthogonal to the detector plane.

Accordingly, there is a need for a DR detector system that provides acompact encasement for housing the glass detector and supportingelectronics so that it fits within the volume of existing standard filmcassettes and meets the requirements of the ISO standard. There is alsoa need for a durable structure that protects the fragile detector fromdamage, due to physical shock or loads applied externally to theencasement. It is also desirable that the DR detector be usable for bothtypical x-ray exam room procedures as well as with portable imagingequipment. There is also a need that the detector be wireless,especially for portable imaging equipment where any electrical cablescan interfere with user operation and handling of the portable detector.

SUMMARY OF THE INVENTION

The present invention is directed to providing a system which addressesthe problems and the needs discussed above.

According to one aspect of the present invention there is provided adigital radiography detector comprising: a housing having first andsecond spaced planar members and four side walls defining a cavity; aradiographic image detector assembly mounted within the cavity forconverting a radiographic image to an electronic radiographic image,wherein the detector assembly includes a detector array mounted on astiffener; and a shock absorbing elastomer assembly located within thecavity for absorbing shock to the detector array/stiffener in directionsperpendicular to and parallel to the detector array/stiffener.

According to another aspect of the present invention there is provided adigital radiography detector comprising: a housing having first andsecond spaced planar members and four side walls; a radiographic imagedetector assembly mounted within the cavity for converting aradiographic image to an electronic radiographic image, wherein thedetector assembly includes a screen and a detector array; and whereinthe detector assembly is bonded to the first planar member of thehousing.

According to a further aspect of the present invention there is provideda digital radiography detector assembly comprising: a digitalradiography detector having a housing having upper and lower planarmembers and four side walls; and a portable assembly detachably mountedto the detector; wherein the portable assembly includes at least onehandle detachably mounted to a side wall of the detector housing.

According to still another aspect of the present invention, there isprovided a digital radiography detector assembly comprising: a digitalradiography detector having a housing having upper and lower planarmembers and four side walls; and a portable assembly detachably mountedto the detector; the portable assembly includes a portable carrierhaving a cavity for detachably enclosing the detector within the cavityof the carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of the embodiments of the invention, as illustrated in theaccompanying drawings. The elements of the drawings are not necessarilyto scale relative to each other.

FIG. 1 is a diagrammatic view of typical x-ray equipment in today'sx-ray examination room.

FIG. 2 is a cross-sectional, elevational, diagrammatic view showing asingle foam preload of an embodiment of the present invention.

FIG. 3 is a sectional, top plan, diagrammatic view showing encapsulatedcorner elastomers of an embodiment of the present invention.

FIG. 4 is a cross-sectional, elevational, diagrammatic view showing analternate single foam preload of an embodiment of the present invention.

FIG. 5 is a cross-sectional, elevational diagrammatic view showing dualfoam preload of an embodiment of the present invention

FIG. 6 is a sectional, top plan diagrammatic view showing cornerelastomer of an embodiment of the present invention.

FIG. 7 is a sectional, top plan, diagrammatic view showing full edgeelastomer of an embodiment of the present invention.

FIG. 8 is a cross-sectional, elevational, diagrammatic view showing theencasement/housing construction of an embodiment of the presentinvention.

FIG. 9 is a cross-sectional, elevational, diagrammatic view showing analternate housing construction of an embodiment of the presentinvention.

FIG. 10 is top plan, diagrammatic view showing an embedded antenna forthe embodiment of FIG. 9.

FIG. 11 is a cross-sectional, elevational, diagrammatic view showing anencasement/housing with exterior bonded elastomer of an embodiment ofthe present invention.

FIG. 12 is a cross-sectional, elevational, diagrammatic view showing anencasement/housing with adhesive bonded screen and detector array of anembodiment of the present invention.

FIG. 13 is a cross-sectional. elevational, diagrammatic view showing anencasement/housing with elastomer in the housing of an embodiment of thepresent invention.

FIGS. 14A, 14B, and 14C are respective top plan, side elevational, andbottom plan diagrammatic views showing an encasement/housing with abattery pack holder and overall thickness of an embodiment of thepresent invention.

FIG. 15 is a top plan, diagrammatic view showing telescoping andflexible antennas of an embodiment of the present invention.

FIG. 16 is a top plan, diagrammatic view showing a detachable handleassembly for portable imaging of an embodiment of the present invention.

FIG. 17 is a top plan, diagrammatic view showing a detachable handle andbattery pack for portable imaging of an embodiment of the presentinvention.

FIG. 18 is a top plan, diagrammatic view of a charging unit for thedetachable handle and battery pack of an embodiment of the presentinvention.

FIGS. 19A and 19B are respective top plan and side elevationaldiagrammatic views showing a detachable carrier of an embodiment of thepresent invention.

FIG. 20 is a top plan, diagrammatic view showing a detachable carrierand battery pack of an embodiment of the present invention.

FIG. 21 is a cross-sectional, elevational, diagrammatic view showing theelectronics and thermal interfaces of an embodiment of the presentinvention.

FIG. 22 is a cross-sectional, elevational, diagrammatic view showingalternate electronics and thermal interfaces of an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The following is a detailed description of the preferred embodiments ofthe invention, reference being made to the drawings in which the samereference numerals identify the same elements of structure in each ofthe several figures.

Referring now to FIG. 1, there is shown diagrammatically typicalprojection x-ray equipment used in an x-ray examination room. As shown,a patient 100 is positioned on a support 102. An x-ray source 104projects x-rays 106 through a body part of patient 100 to form aradiographic image of the body part which is detected by a digitaldetector housed in radiography cassette 108 mounted in support 102.X-ray source 104 is activated and controlled by x-ray generator andcontrol 110. Support (Bucky) 102 can also house an antiscatter grid 112,an auto exposure control sensor 114, 114′ (located above the radiographycassette for general radiography and below the radiography cassette formammography). Detector control 116 is linked to the digital detector incassette 108 and to capture system and exposure control 118. Antiscattergrid 112 and auto exposure control 114, 114′ are linked to x-raygenerator and control 110 which is linked to computer 110.

There are numerous types of x-ray equipment and configurations designedfor specific radiographic procedures. These can include wall-stand,floor-mount, chest, or table units; designed for supine, upright, orother patient orientations. Major manufacturers of traditional x-rayequipment include, for example, Siemens, Philips, and General Electric.It has been estimated that worldwide volumes of traditional x-rayequipment is well over 100,000 units. Because of these large volumes, itis an object of the present invention to replace/retrofit film or CRscreen cassette with a digital radiography detector that fits within thesame cassette volume accepted by x-ray equipment.

An embodiment of the present invention is shown in FIGS. 2 and 3. Asshown, DR detector 200 includes upper housing 202, lower housing 204,secured together and forming a cavity 206. Mounted within cavity 206 aredetector array 208 mounted on stiffener 210, screen (scintillator) 212,compliant foam member 214, elastomer shock-absorbing supports 216mounted on stop ledges 217 of lower housing 206, flex circuits 218connected between detector array 208 and electronics 220. A wirelessinterface 222 is connected to electronics 220. A battery pack 224 ismounted in a compartment 226 of lower housing 204. Battery pack 224 andelectronics 220 are thermally coupled to sheet metal member 228 whichacts as a heat sink for heat generated by battery pack 224 andelectronics 220. X-rays are projected to detector 200 in the directionof arrow A.

Indirect DR systems use an intensifying phosphor screen (scintillator)212 to convert x-ray radiation into visible light. A detailedexplanation of this conversion process and detection system is disclosedin U.S. Pat. No. 5,650,626, issued Jul. 22, 1997, entitled “X-rayImaging Detector with Thickness and Composition Limited Substrate”,inventors Trauernicht et al. The embodiment of FIGS. 2 and 3 has thescintillator screen 212 placed in contact with detector array 208 bymeans of compliant foam member 214 which applies and maintains thisphysical contact. Physical contact between screen 212 and detector array208 can also be applied by means such as a spring or a plurality ofsprings. Further, an index-matching type optical adhesive could be usedto bond screen 212 directly to detector array 208, so that compliantfoam member is not needed. It is important that physical contact bemaintained across the entire active area of the detector array 208, sothat uniform and efficient transfer of the converted visible light isachieved.

To comply with ISO 4090.2001(E) standard, packaging of the detectorarray and supporting electronics becomes very challenging. There islimited space for these components in all directions (X, Y, Z). First,flex circuits connecting the detector array and electronics need to bewrapped underneath the array. Second, use of a self-contained batteryand battery pack within the DR detector is preferred. In order to complywith the 16 mm cassette thickness, the self-contained battery andbattery pack needs to be extremely thin. For example, a lithium polymerrechargeable battery such as Ultralife UBC36106102 could be used. Thistype of rechargeable battery is only 4.0 mm thick. It is noted that thepresent invention is not limited to a self-contained battery, but couldbe energized through an external power source. Detector array 208 isfabricated onto a substrate material such as Corning 1737 display glass,for example, or a substrate with a chemical composition, such asdisclosed in U.S. Pat. No. 5,650,626. Display glass is typically 0.7 mmthick, and susceptible to breakage, especially when a large-area, suchas 43 cm×43 cm, is used. For durability reasons, the detector array 208is attached to a stiffener 210 in an embodiment of the presentinvention. The stiffener is made of a lightweight composite that hassimilar thermal coefficient of expansion to the substrate material, butsignificantly higher bending stiffness than the substrate. For example,the composite can be made of a core using Rohacell IG closed-cell rigidfoam, sandwiched between thin plies of directionally oriented carbonfiber.

Attachment of detector array 208 to stiffener 210 can be applied using adouble-sided pressure sensitive tape such as 3M 9832HL, for example, ora removable thermal release adhesive such as Nitto Denko REVALPHA.Bending stiffness of the composite should be on the order of 10× greaterthan the substrate material. This will result in the compositesupporting the substrate material in such a way as to minimizedeflection under extreme load or shock conditions. Otherwise, fractureor breakage of the substrate material could occur. So that the detector208 and stiffener 210 do not distort under an operational temperaturerange, it is desirable that the Coefficient of Thermal Expansion (CTE)of the detector 208 and stiffener 210 be similar Display glass has a CTEaround 4×10-6 per degrees C., whereas carbon fiber based composites canrange between: −0.5×10-6 and +5.0×10-6 per degrees C., depending on thetype of fiber, fiber orientation, and core material used. The uniquenessof the composite structure is that the fiber type and orientation can beadjusted to obtain desired thermal characteristics. Similar compositestructures are being used today to mount large glass telescope mirrorsfor space exploration.

As shown in FIGS. 2 and 3, the attached detector 208 and stiffener 210are mounted to elastomer supports 216 for protection against externalshock and vibration, which further enhances the durability of theoverall DR detector 200. Four encapsulated elastomer supports 216 areeach located in the four corners of the detector/stiffener panel208/210. The elastomer support 216 should be relatively flexible toabsorb shock. For example, a polyurethane type material with a hardnessof 20-40 Shore A durometer could be used. The elastomer supports 216 areheld against and within mating corners of upper and lower housings 202,204.

As shown in FIG. 4, DR detector 400 includes upper and lower casings 402and 404 mounted to four-sided external frame 406. An internal frame 408is mounted to lower casing 404. Foam layer 410 preloads screen 412,detector 414, stiffener 416 in the direction of arrow 418 against innerframe 408. Inner frame 408 can be attached to stiffener 416 via adhesiveor conventional fasteners for locating components in the lateral or Xdirection. There are column features on the inner frame 408 that locatethe inner frame 408 against lower casing 404. Flexible circuit 420 isalso provided. Elastomer members 421 are used as a buffer againstphysical shock in the X direction, and further aid in keeping thepreloaded components centered in the housing. Further foam layer 410provides shock isolation in the Z direction, while at the same timeprovides an alternate means of isolation in the X direction, throughshearing of the foam layer in the direction of arrow 440. Electronics422 and 424 can have a heat conduction path directly through the lowercasing via thermal pad 426. An antenna 428 and battery 430 are alsoincluded in detector 400.

FIGS. 5 and 6 show a modification of the DR detector shown in FIGS. 2and 3. As shown DR detector 500 includes upper housing 502, lowerhousing 504, secured together and forming a cavity 506. Mounted withincavity 506 are detector array 508 mounted on stiffener 510, screen(scintillator) 512, compliant foam members 514 and 515, elastomershock-absorbing supports 516, flex circuits 518 connected betweendetector array 508 and electronics 520. A wireless interface 522 isconnected to electronics 520. A battery pack 524 is mounted in acompartment 526 of lower housing 504. Battery pack 524 and electronics520 are thermally coupled to structural member 528 which acts as a heatsink for heat generated by battery pack 524 and electronics 520. X-raysare projected to detector 500 in the direction of arrow B. In thisembodiment, foam members 514, 515 support both front and back of thedetector array—stiffener pair 508, 510. There are advantages of thisconfiguration. First, uniform pressure is applied by means of the foamto both sides of the detector array 508 and stiffener 510, resulting inno static deformation of this pair. Second, there will not be anylocalized stress applied to the corners of the pair since the cornerelastomer supports do not encapsulate the pair.

FIG. 7 shows an embodiment of the invention where the corner elastomersupports are replaced with elastomer supports along two full edges ofthe detector. For ease of discussion, only components are shown toillustrate the embodiment. As shown, DR detector 700 includes a housing702, detector array 704, with flex circuits 706. Elongated elastomersupports 708 are located along edges 710 and 712 where flex circuits 706are not located. If flex circuits are needed on all four sides, thisarrangement would not be possible. The advantage of this embodiment isthat having additional contact along the width and length can furtherreduce stress imparted to the detector array 704.

FIG. 8 shows construction of the housing of the DR detector. As shown,DR detector 800 has upper housing 802 and lower housing 804. Upperhousing 802 has upper casing 806 and upper frame 808, while lowerhousing 804 has lower casing 810 and lower frame 812. Lower casing 810has battery pack holder 814. Upper and lower casings 806, 810 arepreferably a lightweight composite, similar to that disclosed in U.S.Pat. No. 5,912,944, issued on Jun. 15, 1999, inventor Budinski et al.The composite disclosed is a composite structure of polypropylene core,sandwiched between thin aluminum sheets. This composite material ismanufactured by Corus, under the product name HYLITE™. In addition tobeing light in weight, this material has high stiffness needed fordurability of the housing. Similarly, a carbon fiber based compositelike that of the stiffener could be used. Several tradeoffs need to beconsidered using a composite material in this application, as follows:a) overall weight, b) material cost, c) radiographic absorption, and d)material stiffness. Several of these parameters are discussed in detailin U.S. Pat. No. 5,912,914, issued Jun. 15, 1999, inventor Dittbenner.

As further shown in FIG. 8, upper and lower frame sections 808 and 812are attached directly to the upper and lower casings 806 and 810,respectively. Frames 808 and 812 add stiffness to the relatively thincasings 806, 810, and are preferably made of a material with a highstiffness to weight ratio. The high stiffness is needed for durabilityreasons, so the housing does not distort under extreme load or shockconditions. Materials such as aluminum, magnesium, and titanium fit inthis category. However, filled thermoplastics can be considered as well,and may have some advantage for potential injection molding the framedirectly to the casings. The lower casing in a DR detector configurationwith self-contained power would require a pocket, e.g., pocket 814, formounting a battery pack holder. A modification of the detector housingof FIG. 8 is shown in FIG. 11. As shown, a thin bonded elastomer 820surrounds the exterior portions of frames 808 and 812. This providesadditional protection against shock and damage to the detector housingand internal components.

An alternate housing construction for a DR detector is shown in FIGS. 9and 10. As shown in FIG. 9, upper and lower casings 902 and 904 of DRdetector 900 are attached to a four sided frame 906. An advantage ofthis configuration is for assembly and test of the detector electronics.The upper casing 902 would first be attached to frame 906. Thisattachment can be done via conventional fasteners or other adhesivefastening means. The upper casing 902 and frame 906 would be placedupside down, where the foam, screen, detector array, stiffener, andinternal frame (see FIG. 4), are placed in that order. All detectorelectronics would then be attached to the internal frame. Having thelower casing not installed at this point, allows for test and debug ofall detector electronics. Once this is completed, the lower casing canbe attached via fasteners or other means, thus preloading the entireassembly.

Another advantage of the latter configuration is for x-ray transmissionand thermal transfer characteristics. The upper casing as previouslydiscussed, should be made of a material that has good x-ray transmissioncharacteristics such as HYLITE™ or carbon fiber composites. The lowercasing is preferably made of a lightweight material that is thermallyconductive such as aluminum or magnesium. A thermally conductivematerial allows a heat dissipation path outside of the detector througha thermal pad material.

Another alternative shown in FIG. 9 is to have a recessed feature aroundthe perimeter of the frame 906 for embedding an antenna. As shown, frame906 has a recess 908 into which antenna 910 is held in place by insert912. The frame 906 is preferably made of a metal that is high instiffness. In order to have enough signal strength for wirelesstransmission, the antenna would be exterior to any metal components.Having the antenna embedded between the exterior of the frame and insertas shown, helps in signal transmission. The insert 912 is preferablymade of a non-metal which does not attenuate the wireless signal, suchas plastic or elastomer. The insert 912 would be wrapped around theperimeter of the frame, and bonded against the recess 908. Additionally,the insert 912 can protrude slightly from frame 906, thus providingadditional shock isolation in the x-direction for the assembly.

Another view of this structure is shown in FIG. 10, and can have aplurality of antennas 910, 910′ embedded in the frame. A plurality ofantennas will increase the likelihood of proper signal transmission oncethe detector assembly is installed in a Bucky. Battery pack holder 914and electronics 916 are also shown.

FIGS. 12, 13, and 14A-14C show another embodiment of the invention. Asshown in FIG. 12, DR detector 1200 includes upper housing 1202 havingupper casing 1204 and upper frame 1206, and lower housing 1208 havinglower casing 1210 and lower frame 1212. Lower casing 1210 has a batterypack holder 1214. Scintillator screen 1216 is attached to upper casingby adhesive 1218 and detector array 1220 is attached to screen 1216 byadhesive 1222. With the understanding that upper casing 1204 isself-rigid, this arrangement can prevent the need for attaching astiffener to the base of the detector array. Additionally, thisconfiguration can allow more space for packaging electronics, since foamis no longer needed. Another variation shown in FIG. 13 is to have anelastomer 1230 between upper housing frame 1206 and upper casing 1204.This would provide additional shock protection. once the detector array,electronics, and all other components are mounted, the upper and lowerhousing members are attached and sealed together. Exterior views of thecomplete DR detector are shown in FIGS. 14A-14C

The DR detector shown in FIG. 15 is useful for an application with awireless interface. As shown, DR detector 1500 has a frame 1502, acasing 1504, electronics 1506, battery pack holder 1508, wirelessinterface 1510, and flexible or telescoping antenna 1512. The flexibleantenna can extend around the detector housing. Some Buckyconfigurations are surrounded with metal, and this can result in signalstrength loss between an internal transmitter within the DR detector andreceiver at the DR system level. In this event, an optional antennawould be necessary to extend outside the Bucky.

Portable imaging is another large market opportunity for future DRsystems. Portable imaging systems are typically used in emergency rooms,trauma center, or operating room, where fast turnaround of the images isnecessary. These systems typically have a mobile-based x-ray source onwheels with a portable cassette using radiographic capture media.Ergonomically, it is desirable to have a handle on these cassettes forportability and to assist during any patient handling and insertion.Further, it is desirable that the portable cassette be extremely lightin weight due to frequent handling of the device. An example of today'sportable digital radiography detectors is the Canon CXDI-50G. Thisdevice has a 35 cm×43 cm specified imaging area, with the overallportable assembly weighing 11 pounds. This is considered too heavy forrepeated and daily handling of these devices. An overall detector weightof 8 pounds is considered to be desirable for ergonomic needs.

It is an object of the present invention to provide a flexible andextensible configuration of the DR detector, so that it can be used forportable imaging, as well as the x-ray exam room applications previouslydiscussed. One embodiment of portable detector configuration is shown inFIG. 16, where a detachable handle can be mounted to a plurality ofedges on the DR detector. As shown, DR detector 1600 includes a casing1602, frame 1604, handle mounting apertures 1605, and battery packholder 1612. A handle 1606 having latches 1608 is detachably mounted todetector 1600. Latches 1608 of handle 1606 engage with apertures 1605along the edge 1607 or 1610 of detector 1600. An advantage of thisconfiguration is that the detachable handle can be mounted for landscapeor portrait imaging, depending on the ergonomic preference or specificimaging procedure. The attachment of the handle to the DR detector caneither be through a quick latch type device, or with conventionalfasteners requiring a tool. The latter attachment means could beadvantaged if orientation change is not frequently required.

FIG. 17 shows a modification of the system of FIG. 16, in which thedetachable handle 1606′ includes rechargeable batteries 1620 to powerthe DR detector 1600, and possibly an antenna 1622 for wirelesscommunication. This extension of the wireless antenna would only benecessary if signal transmission is not adequate as previouslydiscussed, otherwise an antenna embedded in the DR detector housingwould be appropriate for portable imaging. A separate charging unit suchas shown in FIG. 18 can be used to recharge the rechargeable (e.g.,lithium polymer) batteries. As shown, battery charger 1650 has a plug1656 and a terminal 1654 for engaging with a terminal 1624 on handle1606′ when handle 1606′ is mounted in apertures 1652 of charger 1650. Inthis embodiment, the battery pack embedded in the DR detector would nolonger be required. Since the structural components previously discussedare all lightweight composite materials, it is feasible that overallweight of the portable DR detector configuration could achieve 8 poundsmaximum.

FIGS. 19A and 19B show an alternate portable imaging configuration inwhich the DR detector is detachably mounted in a portable carrier. Thisconfiguration provides additional structural rigidity surrounding the DRdetector but also adds additional weight. As shown, DR detector 1900 isdetachably received in cavity 1904 of portable carrier 1902. Latch pin1906 on carrier 1902 locks into aperture 1908 on detector 1900. Thelatch pin facilitates locking and releasing the detector 1900 relativeto the carrier 1902. FIG. 20 shows a portable carrier 1902′ havingrechargeable batteries 1910, antenna 1912, and connector 1914.

It is known that detector arrays used in today's DR systems aresensitive to temperature variations affecting uniformity of thedetector. It is another object of the present invention to provide apassive cooling means to transfer heat away from all heat sourcecomponents within the DR detector. This would include the electronics,battery, and ASIC electronics attached to the flex circuits as shown inFIG. 21. As shown, components of DR detector 2100 include detector array2102, stiffener 2104, air gap 2106, lead shield 2108, structural member2110, thermally conductive member 2112, ASIC 2114, electronics 2116,wireless interface 2118, battery pack 2120, and temperature sensor 2122.Thermally conductive member 2112 is made of thermally conductivematerial such as Panasonic Pyrolytic Graphite Sheet (PGS). This materialis very efficient in transferring heat laterally away from the heatsource (X and Y directions), due to the directional orientation of thegraphite. The thermally conductive material would be sandwiched betweenthe heat sources as shown, and a thermally conductive structural member2110 to further dissipate the heat. A lead shield 2108 may be usedbetween the x-ray source and electronics to absorb radiation and preventpossible damage to the electronics over time. Additionally, lead orother heavy metal could be embedded or attached to the stiffener forsimilar x-ray absorption purposes.

It is preferred that the structural member be separated from thestiffener so that heat is not directly conducted through the stiffenerand detector array. This can be accomplished through air gap 2106, orsome thermal insulating material such as the foam shown in FIG. 5.

A temperature sensor 2122 or plurality of temperature sensors can beattached in as close proximity to the detector array as possible. Thesensor(s) would be used to monitor local or ambient temperature of thedetector array through the electronics, and possibly correct for anytemperature non-uniformities captured during DR detector manufacturing.

FIG. 22 shows another embodiment of thermal management in a DR detector.As shown DR detector 2200 includes detector array 2202, stiffener 2204,flex circuit 2206, lead shield 2208, lower casing 2210, internal frame2212, battery pack 2214, ASIC 2216, Printed Circuit Board(s) (PCBs)2218, electronic component(s) 2220, wireless interface 2222, andthermally conductive gap pad 2224. The embodiment allows transfer ofheat out of the housing through the lower casing. This allows fornatural convection and radiation to remove heat from the outside of thehousing. The ASIC and all primary heat dissipating electronic componentstransfer heat through the thermally conductive pad and the lower casing.A thermally conductive material such as Panasonic PGS can be used forthe thermal pad. Alternatively, a thermally conductive gap pad materialsuch as Bergquist 3000S30 could be used. An advantage of a gap padmaterial is that it will compress and accommodate height differences ofelectronic components, compared with the very thin Panasonic PGSmaterial. Thickness of gap pad materials range from 0.25-3.0 mm,compared with PGS at 0.10 mm thickness only.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

PARTS LIST 100 patient 102 support 104 x-ray source 106 x-rays 108radiography cassette 110 x-ray generator and control 112 antiscattergrid  114, 114′ auto exposure control 116 detector control 118 host PCcomputer 200 DR detector 202 upper housing 204 lower housing 206 cavity208 detector array 210 stiffener 212 scintillator screen 214 compliantfoam member 216 elastomer supports 217 stop ledges 218 flex circuits 220electronics 222 wireless interface 224 battery pack 226 compartment 228structural member 400 DR detector 402 upper casing 404 lower casing 406external frame 408 internal frame 410 foam layer 412 screen 414 detector416 stiffener 418 arrow 420 flexible circuit 421 elastomer member 422,424 electronics 426 thermal pad 428 antenna 430 battery 440 arrow 500 DRdetector 502 upper housing 504 lower housing 506 cavity 508 detectorarray 510 stiffener 512 screen 514, 515 compliant foam members 516elastomer supports 518 flex circuits 520 electronics 522 wirelessinterface 524 battery pack 526 compartment 528 structural member 700 DRdetector 702 housing 704 detector array 706 flex circuits 708 elastomersupports 710, 712 edges 800 DR detector 802 upper housing 804 lowerhousing 806 upper casing 808 upper frame 810 lower casing 812 lowerframe 814 battery pack holder 820 elastomer 900 DR detector 902, 904upper and lower casings 906 frame 908 recess  910, 910′ antenna 912insert 914 battery pack holder 916 electronics 1200 DR detector 1202upper housing 1204 upper casing 1206 upper frame 1208 lower housing 1210lower casing 1212 lower frame 1214 battery pack holder 1216 scintillatorscreen 1218 adhesive 1220 detector array 1222 adhesive 1230 elastomer1500 DR detector 1502 frame 1504 casing 1506 electronics 1508 batterypack holder 1510 wireless interface 1512 antenna 1600 DR detector 1602casing 1604 frame 1605 apertures  1606, 1606′ handle 1607 edge 1608latches 1610 edge 1612 battery pack holder 1620 rechargeable batteries1622 antenna 1624 terminal 1650 battery charger 1652 apertures 1654terminal 1656 plug 1900 DR detector  1902, 1902′ portable carrier 1904cavity 1906 latch pin 1908 aperture 1910 rechargeable batteries 1912antenna 1914 connector 2100 DR detector 2102 detector array 2104stiffener 2106 air gap 2108 lead shield 2110 structural member 2112thermally conductive member 2114 ASIC 2116 electronics 2118 wirelessinterface 2120 battery pack 2122 temperature sensor 2200 DR detector2202 detector array 2204 stiffener 2206 flex circuit 2208 lead shield2210 lower casing 2212 internal frame 2214 battery pack 2216 ASIC 2218PCB(s) 2220 electronic component(s) 2222 wireless interface 2224thermally conductive gap pad

1. A digital radiography detector assembly comprising: a digitalradiography detector having a housing having upper and lower planarmembers and four side walls; and a portable assembly detachably mountedto the detector; wherein the portable assembly includes at least onehandle detachably mounted to a side wall of the detector housing.
 2. Thedetector assembly of claim 1 wherein the at least one handle includesone or more of a battery and antenna that can be connected to thedetector when the handle is mounted to the detector housing.
 3. Thedetector assembly of claim 1 wherein the portable assembly includes atleast two handles detachably mounted to at least two side walls of thedetector housing.
 4. The detector assembly of claim 1, furthercomprising a scintillator screen and a detector array bonded to eitherthe upper or lower planar member of the housing.